• Journal of the Korean GEO-environmental Society
• /
• v.20 no.5
• /
• pp.31-38
• /
• 2019

Recently, there has been an increasing number of ground subsidence (sink-hole) in the downtown areas, and in such a case, it is important to minimize accidents and passages through prompt recovery. With respect to the present recovery method for ground subsidence, the methods of applying the back filling after excavating the ground subsidence or using the grouting injected materials to restore the ground are mostly used, but there has been few studies on materials used for recovering the ground subsidence. Therefore, in order to clarify the characteristics of back filling materials used in the ground subsidence, this study uses the environment-friendly hardening agent to improve the dredged clay, and then, the mixture ratio of hardening agent and mixture ratio of decomposed granite soil is changed to cure for 3, 7, 14 and 28 days to analyze the intensity characteristics of the unconfined compression, and it was compared with the unconfined compression intensity for the previously used cement, a hardening agent. In order to evaluate the characteristics of intensity on the back filling materials, the C.B.R test was carried out, and for the review on whether the back filling materials influence on corrosion of water and sewer pipes and others, the soil non-resistance test was carried out. As a result of the test, for the case of the recovery work of the ground subsidence that requires urgency, it is considered as prudent if the hardening agents of 12% are integrated to cure for 3 days or longer, and for not having the influence on the corrosion of the gas tube or water pipes, it is proposed to mix for 30% or more of the decomposed granite soil. Door model test were conducted To confirm the bearing capacity characteristics of the solidified layer.

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.12
• /
• pp.71-78
• /
• 2011

This paper aims to present the evaluation of engineering characteristics and reusing possibility of waste powders produced in dolomite and limestone nonmetal mining by physical and mechanical experiments on compaction, uniaxial compressive strength, permeability, chemical composition, and so on. Granite soil, 2 types of limestone waste powder, and 1 type of dolomite waste powder were used for main materials, and cement and bentonite were used for admixed materials in this experiments. The findings based on the experimental results are the severe difference of chemical composition of the dolomite & limestone waste powder and the crushed rock waste powder, and the outstanding of engineering characteristics of the dolomite waste powder with high content of MgO compared with the limestone waste powder. The engineering properties on compaction, uniaxial compressive strength, and permeability are enhanced with increase of admixed ratio of waste powder on granite soil. From the experimental results, it can be suggested that the dolomite waste powder admixed with in-situ granite soil is useful as geo-materials with considering of distribution costs.

• Proceedings of the Korean Fiber Society Conference
• /
• 2002.04a
• /
• pp.85-88
• /
• 2002

보강섬유란 지반구조물 중 토질재료 즉, 흙과 혼합되어 사용되는 토목용 합성섬유인 geofibers를 의미하며, 주로 흙의 응집력을 보강하는 기능을 가지고 있다. 일반적으로 토질재료는 비탄성 재료로써 약 5%정도의 변형에 파괴되는 역학적 성질을 가진 재료이며, 입자크기에 따라 그 적용범위가 매우 다양하다. 특히, 국내토양의 대부분을 차지하고있는 화강풍화토를 복토재로 사용할 경우 응집력이 약하여 지반구조물의 보강효과가 크게 떨어지는 문제점을 안고 있다. (중략)

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.211-216
• /
• 2003

굴폐각은 굴양식 후 남는 것으로 남해안에서 주로 집중적으로 발생하는데 연간 28만톤의 발생량 중 상당양은 폐기물로 계속 누적되고 혹은 불법매립되어 환경오염 문제까지 발생시키고 있다. 본 연구에서는 산업폐기물로 분류되는 굴패각을 지반공학 분야에서 활용하기 위한 대안으로 해성점토와 혼합하여 매립재료로써의 적용성을 평가하기 위하여 대형 압밀기를 이용하여 실험을 실시하고 이를 토대로 기초자료를 획득하고자 하였다. 원형의 굴패각을 파쇄하여 입도별로 분류하고 이중 사질토 입경 크기의 재료에 대한 기본 물성치를 평가하고 지반 재료로써의 적용성를 분석하였다. 해성점토 내의 굴패각입자의 혼합비를 변화시켜 만들어진 혼합토에 대한 압밀 실험 결과 굴패각의 혼합율이 증가할수록 체적변화율이 작게 되고, 침하 속도는 빠르게 증가함을 알 수 있었다. 이는 압밀응력의 일부를 굴패각 입자의 골격구조가 부담함으로써 실제 점토부분에 작용하는 압밀응력은 굴패각 혼합율이 증가할수록 작아지는 것으로 판단된다.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.3
• /
• pp.53-58
• /
• 2012

In general, sand compaction pile(SCP) method and gravel compaction pile(GCP) method have been mainly used to reinforce soft soils such as soft clay or loose sandy ground. But the sand compaction pile method has problems such as lack of sand supply and destroying the nature while collecting sand, the gravel compaction pile method has a problem such as decreased permeability of the drainage material due to clogging. Recently, the study to replace sand with bottom ash which has similar engineering properties with sand is in active. As a fundamental research on bottom ash mixture compaction pile utilizing bottom ash, its behavioral characteristics depending on granular materials and replacement ratio has been simulated numerically. In particular, Settlement Reduction Ratio(SRR) according to the distance from the center of pile was calculated. The main findings were as follows. Change values of Mixture Compaction Pile's SRR according to granular materials showed similar patterns and stiffness of the composite soil is increased depending on the replacement ratio so SRR showed decreased patterns. Especially, when the replacement ratio is in 20~40%, it increase significantly. When the replacement ratio is over 40%, it increase slowly. When considering the economics, 30~40% replacement ratio is appropriate.

• Journal of the Korean GEO-environmental Society
• /
• v.21 no.3
• /
• pp.5-11
• /
• 2020

Recently, ground pits that have been occurring frequently in urban areas are hindering traffic flow and causing property damages and loss of human life, acting as factors that are threatening the safety of citizens. Therefore, sunken ground must be quickly restored and provisions must be made for additional damage but current domestic detailed standards regarding ground pits and accurate definitions regarding causes and measures to be taken for reoccurrences are lacking. Restoration methods of sunken ground include backfilling by reusing sunken soil or other fill material and paving the road and while this is the most often used method, this only prevents ground from sinking temporarily and can not serve as a fundamental solution. Also, additional ground pits can occur on ground that is reinforced using this method due to faulty backfill material or faulty hardening. This study used Eco-friendly High-Strength Material (EHSM) as restoration material that can be used in the restoration of underground cavities that have occurred due to ground subsidence to analyze the engineered characteristics of modified dredging clay and test pieces made from changed ratios of EHSM and weathered granite soil were uniaxial compression tests were conducted and freezing-thawing tests were conducted to study strength properties according to environmental changes of restoration material, and after tests were concluded by each level, uniaxial compression tests and dynamic elasticity tests were conducted for intensity analysis. Also, to evaluate strength characteristics of the restored ground, dynamic plate load tests were conducted to verify the improvement effectiveness of the restored ground.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.5D
• /
• pp.505-512
• /
• 2010

Generally, the repeated traffic loading condition should be considered to predict the long-term deformation on road foundations or foundation systems. However, it is not easy to estimate long-term deformation on multi-layered system like roads and railways. For more quantitative analysis, mechanistic-empirical approach requires proper analytical tool, material's model, and material properties of foundation geomaterials under both traffic and environmental loadings. In this study, therefore, laboratory data from the long-term repeated load triaxial tests were used to predict accumulated deformation on pavement foundations and the results were analyzed based on the nonlinear models and stress state considered. All these results are presented and verified on laboratory based scale using the finite element analysis with the deformation characteristics of foundation geomaterials at various stress states.

• Journal of the Korean Geosynthetics Society
• /
• v.13 no.1
• /
• pp.41-52
• /
• 2014

Decomposed granite soil is likely to lose its strength when exposed to air or water. Such a geomaterial is weathered by wetting-drying or freezing-melting. In this study, resonant column tests were conducted to figure out the dynamic characteristics of granite soil that has affected by environmental changes like weathering condition. The results show that wetting-drying weathering condition is the most affective parameter on the dynamic characteristics of granite soil. In the meantime, artificial weathering conditions such as freezing-melting has less affection at first and getting increase as the process repeats constantly.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.4D
• /
• pp.571-576
• /
• 2011

In general, conventional road pavements are designed under the assumption that the shear strength of geomaterials are under saturated state. In reality, however, most of the pavement geomaterials exists under the unsaturated state. To deal with this gap between saturated and unsaturated conditions, in this paper, unsaturated shear strength was estimated using the results from the triaxial compression test and soil-water characteristics curves. Then, yield loads were assessed using 2-Dimensional finite element method with the selected nonlinear elastic model and the Mohr-Coulomb yield criteria. In addition, various unsaturated condition and surface layer effects on the yield load of granular materials were identified. Therefore, the results demonstrated would provide a possibility to estimate bearing capacity of paved or unpaved roads using unsaturated soil mechanics.

• Land and Housing Review
• /
• v.12 no.4
• /
• pp.127-137
• /
• 2021

Grouting has been widely used to enhance the strength of the ground and prevent waterflow into the underground space in the geotechnical engineering field. Cement with bentonite can be considered a helpful grouting material because the bentonite has a swelling ability with water. Therefore, it is essential to evaluate the characteristics of grouting materials according to the mixing ratio for a successful grouting process. In this regard, the study investigated the viscosity and bleeding characteristics of grouting materials according to the mixing ratio (i.e., water/cement ratio and bentonite/cement ratio). In the experimental result, the viscosity increases with decreasing water/cement ratio and rising proportion of bentonite by weight of cement. However, the results of the bleeding ratio show the tendency is inversely proportional to the viscosity results. Bentonite was explored in terms of the viscosity and bleeding criterion. This result is expected to be meaningful to determine the optimized mixing ratio of bentonite-cement in the grouting field.